Electric bell, buzzer or similar device



July 31, 1956 c. P. PEREZ ELECTRIC BELL, BUZZER OR SIMILAR DEVICE 2Sheets-Sheet 1 Filed April 17, 1953 R m m m P De re 2:

July 31, 1956 c. PEREZ 2,757,365

ELECTRIC BELL, BUZZER OR SIMILAR DEVICE Filed April 17, 1953 2Sheets-Sheet 2 BY 74pm United States Patent Ofi Fice 2,757,365 PatentedJuly 31, 1956 2,757,365 ELECTRIC BELL, BUZZER OR SIMILAR DEVICE CarlosPablo Perez, Martinez, Argentina Application April 17, 1953, Serial No.349,461 2 Claims. (Cl. 340-393) The present invention relates to anelectric bell, buzzer or similar device and has for its object theprovision of an improved device operating directly with alternatingcurrent from power mains but producing a harmless voltage at the callbuttons.

By the use of the present invention a considerable economy is achieved,since the use of a separate transformer is avoided.

Several devices have already been developed to avoid the use of thetransformer previously required for the operation of bells on the powermains. However, none of them achieved the results obtained by the use ofthe present invention with the same economy. All previous devicesrequired, for equal results, more iron, more copper or more of bothmaterials and some even more workmanship.

The invention, in either of its embodiments, as bell, buzzer or combinedbell and buzzer offers the further advantage that the usual sparking atthe make and break points, will all its inconveniences, never occurs.

According to this invention, an electric bell or buzzer signal device isprovided comprising a closed substantially rectangular magnetic core, acoil (primary winding) on one limb of said core, for connection toalternating current mains, at least one coil (secondary winding) on thelimb of said core opposite the primary winding and placed very close tothe primary, that is, practically touching it, so as to make themagnetic circuit a bare minimum, and generating (the secondary coil) alow harmless voltage when the primary winding is connected to the mains;an armature, partially surrounding at least one of the coils mentionedand extending from one to the other of the unwound limbs of the core,and a bell or buzzer call circuit having circuit closing buttons (orother circuit closing devices) in circuit with the secondary winding.

In order that the invention may be clearly understood and readilycarried into practice, a preferred embodiment thereof has been shown byway of example in the accompanying drawings, in which a combined belland buzzer in accordance with the present invention is illustrated andin which:

Figure 1 represents the side of the device facing the wall.

Figure 2 is a sectional view taken along the line AA of Figure 1.

Figure 3 represents the other side of the device shown without the bellbody 10 and the bridge 11 (Figure 2).

Figure 4 shows only the essential parts of Figure 2.

Figure 5 is a wiring diagram.

Fig. 6 is a diagrammatic side elevation showing the device employed as arelay.

The drawings show a bell which, in addition to the advantages alreadymentioned, possesses that of being able to operate either as a bell oras a buzzer.

As represented in Figs. 15, the electric sound signalling deviceaccording to the present invention comprises a closed magnetic core 1,made of magnetic laminations, and two windings 2 and 3, wound on it, ofwhich the primary 2 is connected at one end by a conductor 4 and at theother by a conductor 5 to the supply terminals of the power mains. Thetwo coils 2 and 3 are very near to each other, making in this way themagnetic circuit an absolute minimum. These two coils 2 and 3 havenumbers of turns such that when coil 2 is connected to the supply lines,a low harmless voltage is generated on coil 3. The ends of thissecondary winding 3 are connected, by means of leads 23 and 24, to thecall buttons 25.

A ferromagnetic armature 6 is elastically fixed to one of the remainingunwound limbs of the core by means of screw 8 and its own resilient part9. This armature forms a magnetic leakage path extending from said oneof the unwound limbs into proximity with the other, with the coil 2 atone side of this leakage path and the coil 3 at the other side thereof.Thus flux generated by the coil 2, depending on whether the circuit ofcoil 3 is open or closed, passes almost entirely through the coreportion surrounded by coil 3, or in substantial part through the leakagepath via armature 6. In the especially compact arrangement shown, thearmature is offset as shown in Fig. 4 to bridge over or surround one orboth of the coils 2 and 3 partially, making it possible to place thesewindings very near to each other. The free end 7 of this armature 6 isshaped in the form of a hammer to strike the bell body 10.

A nonmagnetic bridge 11, fixed to the other side of the unwound limbs ofthe core 1 by means of screws 8 and 17, supports the bell body 10 bymeans of screw 12 and spring 13, so that the bell body may be fixed inany desired position. A spring 15 and screw 16 make it possible toadjust the position of the armautre 6.

The whole embodiment is fixed to the box 18 by means of the aforesaidscrews 8 and 17. Springs 19 make this mounting elastic and keep the nutstightened.

Around the small magnetic core 14, fixed to the box 18 by means of screw27, is Wound the coil 20, connected to conductors 22 and 24. A resilientferromagnetic armature 21 closes the magnetic circuit.

Conductors 23 and 24 are branched to the bell call buttons 25. Thebuzzer call buttons 26 are connected to leads 22 and 23.

When no button is depressed the transformer runs on no load and, as iswell known, the largest part of the primary flux closes itself throughthe secondary coil 3, the leakage flux being negligible.

When one of the buttons is depressed, the secondary circuit is closedand an alternating current passes through coil 3, the primary currenttherefore increasing. The primary and secondary fluxes are, inaccordance with Lenz law, constantly opposing each other. The leakageflux is therefore considerably increased, and, as the largest part of ittraverses the armature 6, this armature is strongly magnetizedalternatively and vibrates at a frequency determined by the frequency ofthe current.

The hammer 7, therefore, will strike the bell body 10 and the devicewill operate as a bell.

If one of the buttons 26 is depressed, the secondary circuit is closedthrough coil 20, of large impedance compared to that of coil 3. Theauxiliary magnetic core 14 is then magnetized alternatively and thearmature 21 is therefore forced to vibrate. The device will operate as abuzzer. As the current traversing coil 3 is small, the leakage flux willbe weak and the armature 6 will not be magnetized enough to vibrate,remaining therefore at rest.

It is obvious that if it is desired to construct a device which willfunction exclusively as bell, or buzzer, the coil 20, its core andarmature 21, as well as call buttons 26, will have to be eliminated.Also, in the case of a device for operation only as a buzzer, the bellbody 10 and hammer 7 will be unnecessary. Springs 13, 15 and 3 19 canalso be omitted in either case, even in the combined bell buzzer, whichwill make the embodiment rigid and the regulation thereof somewhat moredifficult.

As a relay mechanism the device is applicable in all cases in whichalternating power current is available and it is desired that thevoltage at the control point shall be low. An exemplary arrangement ofsuch application of the invention is indicated in Fig. 6 in which theelements bearing numbers corresponding to those in Figs. 1-5 are thesame, but in which the armature 7 carries a contact 27 that is movedagainst contacts 28 and 29, which are resiliently mounted (as indicatedby springs 30) to follow the vibratory movement of the armature 6-7relatively close to the core 1, when the secondary circuit 3 (see Fig.5) is closed; but which do not rise far enough to follow the armature6-7 when it moves to the more remote position it occupies when thecircuit of secondary 3 is open.

The operation of the device when used as just indicated will be readilyunderstood and requires no further explanation for those skilled in theart.

Obviously a number of constructional and detail modifications may bemade in the device without departing from the nature and scope of thepresent invention, as defined in the appended claims.

Having now particularly ascertained and described the nature of thepresent invention and the manner in which the same is to be performed,what I claim is:

1. A signal device comprising a closed substantially rectangularmagnetic core, a primary winding on one leg of said core for connectionto alternating current mains, at least one low voltage secondary windingon the leg of said core opposite said primary winding and placed veryclose to said primary winding, a movable armature having end portionslying proximate to the third and fourth legs of said rectangular coreand having an outwardly displaced central portion surrounding a part ofat least one of said windings, and contact means for closing the circuitof said secondary winding, said armature vibrating in a plane normal tothe plane of said core, and without contacting said partially surroundedwinding when the circuit of said secondary winding is closed.

2. A signal device according to claim 1 further comprising a coil woundon an auxiliary core, the said coil having a large impedance compared tothat of said secondary Winding, a resilient vibratable armaturecomprising part of the magnetic circuit of said auxiliary core, and acircuit, including said coil and means for closing the circuit thereof,connected in series with said secondary winding.

References Cited in the file of this patent UNITED STATES PATENTS1,048,913 Stuart Dec. 31, 1912 1,622,862 Detmers Mar. 29, 1927 1,979,127Warrick Oct. 30, 1934 2,002,433 Cowles -a May 21, 1935 FOREIGN PATENTS464,149 Great Britain Apr. 13, 1937

